Precalciner Geometry Optimization Considering H2O and CO2 Heat Transfer Fluid for Cement Production
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Global demand for adaptable and rapidly deployable construction solutions in offshore, coastal, and fluvial environments continues to rise, driven by pressing needs to develop energy platforms, improve coastal resilience, and support emergency response in the face of natural disasters. Increased investment in human-made coastal infrastructure, such as piers, support structures for power lines, offshore wind farms, and seawall protection systems, further underscores this trend. This study investigates the development of printable concrete mixtures for underwater environments using seawater as a replacement for freshwater, using a 3D printing syringe-based extrusion system. The effect of seawater addition and the printing medium (in air vs. underwater) was assessed via rheological and mechanical performance characterization. The results indicate rheological properties are favorable for seawater adoption by producing mixtures with higher yield stress and viscosity with the same levels of admixtures used for freshwater. Seawater-based mixtures demonstrated superior dimensional stability compared to freshwater counterparts, maintaining cross-sectional geometry, while compressive strength results showed no statistical differences between in-air and underwater samples. However, flexural strength was significantly influenced by geometry and printing medium. These findings establish critical rheological parameters for printable underwater mixtures and highlight the need for optimized curing strategies and layer bonding techniques to improve interfacial strength in underwater 3D printing applications.
Multiple tests with eddy current proximity gage for determining thickness of concrete pavements
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The Curiosity rover landed on Mars in August 2012 to explore the sedimentary history and to assess the habitability of Gale Crater. After 1200 sols of surface operations and over 12 km of traverse distance, the mineralogy of 10 samples has been determined by the CheMin X-ray diffractometer (XRD) and the chemical composition of nearly 300 targets has been established by the Alpha Particle X-ray Spectrometer (APXS). Light-toned fracture zones containing elevated concentrations of silica have been studied by Curiosity's instruments to determine the nature of the fluids that resulted in the enrichment of SiO2. Multiple fluid exposures are evident, and the chemistry and mineralogy data indicate at least two aqueous episodes may have occurred under acidic conditions.
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